Transcript Measurement of energy intake.

Adrenal Cortex
Prof. K. Sivapalan
Structure of Steroid Hormones.
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Classification of steroids
• Mineralocorticoids- aldesteron
• Glucocorticoids- cortizol
• Sex hormones
•
androgens
•
estrogens
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Mechanism of Action of Steroids.
• Transport- bound to globulin- Transcortin.
• Binds to receptors in cytozol, transported
to Nucleus and act on transcription.
• Direct action on membrane and enzymes.
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Glucocorticoids.
• Half-life- 60-90 minutes
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Effects on Carbohydrarte
Metabolism.
• In Liver, increases gluconeogenesis.
– Increase transport of AA into cells of liver.
– Gluconeogenic enzymes increased in liver.
– Entry of AA into other tissues prevented.
• Reduces glucose utilization by cells.
• The above changes are not seen in Heart,
Brain, and red cells.
• Increases blood glucose level.
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Effects on Protein Metabolism.
• Reduce protein synthesis.
• Increase catabolism of cellular protein.
• Reduce RNA in muscles and lymphoid
tissue.
• Increase blood Amino acids.
• Increase protein synthesis in liver, plasma
proteins.
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Effects on Fat Metabolism.
• Increased lypolysis from adipose tissue in
limbs.
• Fat storage increased in face and trunk.
• Increased plasma FFA.
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Other Effects of Glucocorticoids.
• Permissive action:
– Catacholamines- calorigenesis, lypolytic
action, pressure responses, bronchodilation.
– Glucagon- same as above.
• Vascular reactivity:
– Smooth muscle tone requires steroids.
– Capillaries require steroids for normal
permeability [absence increases permeability]
• Essential for life.
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Other Effects of Glucocorticoids
• Nervous system:
– Reduction results in personality changes- irritability,
apprehension and inability to concentrate.
– Electroencephalogram changes: slower than normal
A rhythm.
– Increase results in reduced threshold for convulsions.
• Water Metabolism:
– Deficiency leads to inability to excrete water.
Increased ADH and reduced GFR observed which
are repaired by glucocorticoids only.
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Other Effects of Glucocorticoids
• Bone- reduce protein matrix and causes
osteoporosis.
• Blood and Immunity:
– Increased RBC, nutrophils, platelets.
– Reduced eosinophils, basophils, lympho cytes and all
immune responses at high doses.
– Use as anti-inflammatory drug.
• Resistance to stress:
– High levels of corticoids needed to cope with stressful
conditions. [Essential for life]
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Effects of Mineralocorticoids.
• Half life- 20 minutes.
• Distal tubule of kidney- sodium absorption
in exchange of potassium and hydrogen.
Blood volume cannot be maintained
without this action.
• *Essential for life.
• Similar action seen in sweat glands,
salivary glands and gastric glands.
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Effects of Sex Hormones
• Secretion increases at puberty.
• Androgens are responsible for acne in
males and females.
• All other actions done by sex hormones
secreted by testis and ovary.
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Regulation of secretion.
• Corticotrophin
Releasing hormone
[CRH] stimulates
ACTH which
stimulates
glucorticoids.
• Renin- angeotensin
system regulates
aldesteron secretion.
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Diurnal Variation of Secretion.
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Other factors that stimulate CRH
• Trauma- nociceptive pathways
• Emotion- lymbic system
– Emotional stresses, fear, anxiety,
apprehension
• Baro receptors throw Nucleus Tractus
Solitarius inhibit.
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Stimuli that increase aldesteron
secretion.
• Glucorticoid also increased,
–
–
–
–
Surgery.
Anxiety.
Physical trauma.
Haemorrhage.
• Glucocorticoid unaffected:
–
–
–
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High potassium intake.
Low sodium intake.
Inferior vena cava constriction in throax.
Standing.
Secondary to congestic cardiac failure, cirrhosis,
nephrosis.
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Adreno Cortical Insufficiency.
• Acute- adrenal crisis:
– Head ache, lassitude, confusion,
restlessness, vomiting, abdominal or costovertibral pain, circulatory collapse,
unconsciousness, death.
• Chronic- Addison’s disease.
– Mineralocorticoid insufficiency alone is rare.
– Mixed insufficiency is common.
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Addison’s disease.
• Weakness and fatigability.
• Weight loss and dehydration.– Increased sodium excretion, water diuresis, reduced
appetite and GIT function.
• Hypotension and small heart- dizziness,
syncopal attacks.
• GIT- reduced acid secretion, reduced motility.
• Nervousness and mental symptoms.
• Precipitation of crisis in stress.
• Pigmentation- depends on the cause.
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Pigmentation due to ACTH.
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Hyper Aldesteronism.
• Primary hyper aldesteronism– tumor- Conn’s Syndrom.
• Secondary Aldesteronism– Cardiac failure, renal disease, cirrhosis.
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•
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Hypokalaemia.
Slight increase in ECF and blood volume.
Slight increase in plasma sodium.
Hypertension.
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Hyper Adrenalism- Cushings
Disease.
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•
•
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Redistribution of fatMoon face.
Fat pads of neck.
Pendulous abdomen.
Buffalo hump.
Striae in skin.
Thin extremities.
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MOON Face.
Same
Twinperson
sisters before
with and
and
without
after treatment.
moon face.
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Other Features of Increased
Glucocorticoids.
• Red face- polycythaemia.
• Thin skin, wasting of muscles, osteoporosisweakness and backache.
• Poorly healing wounds.
• Systolic hypertension- sodium retention,
angeotensin increase or direct effect.
• Diabetes mellitus.
• Mood changes- increased appetite, insomnia,
euphoria, toxic psychosis.
• Hypokalaemia- mineralocorticoid action.
• Hirsutism- increased androgens.
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Effects if increased Androgens.
• Female fetus- male type of genitalia.
• Male fetus- facilitated development of genitalia.
• In childhood- stimulation of growth but early
closure of epiphysis and short stature.
• Prepubertal boys- precautious puberty without
testicular development.
• Adult male- no significant changes.
• Pubertal and adult females- male features.
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